Offshore gas flare apparatus

ABSTRACT

APPARATUS FOR CONDUCTING WASTE GAS PRODUCED FROM AN OFFSHORE WELL EXTENDING INTO THE FLOOR OF A BODY OF WATER TO A REMOTE LOCATION. A PLATFORMS STRUCTURE RESTS ON THE WATER FLOOR AND INCLUDES A GAS LINE IN SELECTIVE FLUID COMMUNICATION WITH THE WELL, THE GAS LINE LEADING TO THE REMOTE LOCATION. A GAS FLARE PIPE IS BUOYANTLY SUPPORTED IN A VERTICAL POSITION AT THE REMOTES LOCATION AND IS FLUID COMMUNICATION WITH THE GAS LINE. THE SUPPORT FOR THE PIPE INCLUDES A RELATIVELY SHORT SPAR BUOY ANCHORED TO THE FLOOR OF THE BODY OF WATER THROUGH AN ELONGATED FLEXIBLE CABLE PIVOTALLY ATTACHED THERETO. IN THIS MANNER, WASTE GAS FROM THE WELL MAY BE BURNED OFF (OR VENTED TO THE ATMOSPHERE) WHILE THE SUPPORT ALLOWS FOR MOVEMENT OF THE GAS FLARE PIPE WITH WATER MOTION.

y 0, 1972 J. w. KUBASTA 3,666,395

OFFSHORE GAS FLARE APPARATUS Filed July 29, L970 2 Sheets-Sheet l I I T;f

WH 27 25 3O INVENTOR. JAMES W. KUBAS TA A WMM ATTORNEY May 30, 1972 J.w. KUBASTA OFFSHORE GAS FLARE APPARATUS 2 Sheets-Sheet Filed July 29,L970 FIG. 3

v INVENTOR. JAMES W. KUBASTA ATTORNEY United States Patent O 3,666,395OFFSHORE GAS FLARE APPARATUS James W. Kubasta, Metairie, La., assignorto Shell Oil Company, New York, N.Y. Filed July 29, 1970, Ser. No.59,247 Int. Cl. F23c 9/00 U.S. Cl. 431-202 Claims ABSTRACT OF THEDISCLOSURE Apparatus for conducting waste gas produced from an offshorewell extending into the floor of a body of water to a remote location. Aplatform structure rests on the water floor and includes a gas line inselective fluid communication with the well, the gas line leading to theremote location. A gas flare pipe is buoyantly supported in a verticalposition at the remote location and is in fluid communication with thegas line. The support for the pipe includes a relatively short spar buoyanchored to the floor of the body of water through an elongated flexiblecable pivotally attached thereto. In this manner, waste gas from thewell may be burned off (or vented to the atmosphere) while the supportallows for movement of the gas flare pipe with water motion.

BACKGROUND OF THE INVENTION Field of the invention The invention relatesto offshore gas flares; and, more particularly, to apparatus forconducting waste gas produced from an oflshore well to a remote locationwhere the waste gas is burned ofl.

Description of the prior art In offshore drilling and/or producingoperation, it is necessary to burn waste gas from wells, and it isdesirable to position the resulting flare at some distance away from thedrilling platform. This involves providing a pipe for conducting the gasfrom the well to a point above the surface of the water, which may be100 feet deep, for example.

SUMMARY OF THE INVENTION It is an object of the invention to provide anoffshore gas flare line comprising a pipe extending from a point belowthe surface of the water to a point above it and means for anchoring thepipe and for supporting it in a substantially vertical position.

Another object of the invention is to provide an offshore gas flare linecomprising a pipe extending from a point below the surface of the waterto a point above it and means capable of yieldably supporting the pipein a substantially vertical position whereby the pipe may be deflectedaway from its upright or vertical position, and may assume an inclinedposition, upon being struck by a passing boat or other object, and iscapable of righting itself quickly after being so deflected.

Another object of the invention is to provide an offshore gas flareline, and an anchor and a float therefor, which are resistant to theaction of wind and waves.

These and other objects are preferably accomplished by providing a gasline in selective fluid communication with an underwater well, the gasline leading to a remote location. A gas flare pipe is buoyantlysupported in a vertical 3,666,395 Patented May 30, 1972 BRIEFDESCRIPTION OF THE DRAWING FIG. 1 is a vertical sectional view ofpreferred apparatus for carrying out my invention; and

:FIGS. 2 through 4 are vertical sectional views of the apparatus of FIG.1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 of thedrawing, a portion of an olfshore platform structure 10 is shown restingon or fixed to the floor 11 of a bottom of water, such as an ocean 12.Structure 10 is supported by a plurality of legs, only one of the legs13 being shown in FIG. 1. Suitable bracing 14 extends between theplatform structure legs as is Well known in the art. However, although aplatform structure 10 is shown permanently anchored in place on floor11, the techniques of my invention are applicable to any offshorestructure which may be temporarily anchored in place, such as a floatingplatform (not shown) held in place by selectively releasable anchors orthe like (also not shown). In all cases, however, the platform structureis in selective fluid communication with an underwater wellhead, as forexample, wellhead structure 15 of FIG. 1 which communicates with ahydrocarbon-producing well 16 extending into the ocean floor 11. A pipestring 17 or the like is in fluid communication with wellhead structure15 and extends to a working platform 18 on structure 15.

Preferably, a railing 19 extends longitudinally along one of the legs ofplatform structure 15, such as leg 13in FIG. 1. A gas pipe 20 isattached to structure 15 along a portion of the railing 19. In otherwords, pipe 20 has a first riser portion 21 extending from workingplatform 18 generally parallel to leg 13 and fixedly Secured thereto bymeans of a plurality of clamps 22 on either leg 13 or railing 19 or bothas shown. The terminal portion 23 of pipe 20 at working platform 18 isadapted to be selectively secured to and in fluid communication withpipe string 17, as for example, through a connecting pipe portion 24.Obviously, portion 24 may be adapted to be disconnected from terminalportion 23 of pipe 20 by any suitable means and suitable valves andcontrol means therefore may also be provided. Further, other types ofarrangements may be used for conveying waste gas from well 16 and pipestring 21 and into gas pipe 20.

A second portion 25 of gas pipe 20 extends outwardly from and generallyhorizontal to platform 10 to a location remote from structure 10. Thesecond portion 25 is generally flexible and comprised of a plurality ofhose sections. In such a manner, waste gas may be conducted from well 16some distance away prior to burning it. Riser portion 21 may beselectively disconnected from second portion 25 by means of aflange-type releasable connector 26 located at the junction of riserportion 21 and second portion 25 adjacent railing 19. In like manner, aplurality of similar connectors 26 may be disposed along the secondportion 25 of gas line 20 for selectively adding on and subtractingsections thereof to thus vary the overall length of portion 25.

A plurality of hose weights 27 are also disposed along portion 25 of gasline 20 for providing a slight negative buoyancy to line 20. Weights 27may be added or removed, as desired, to so vary the buoyancy of secondportion of line 20. As can be seen in FIG. 1, second portion 25 of gasline 20 extends from platform structure at some point below the meanwater line 58 and at some point substantially above the floor 11 ofocean 12.

A gas flare pipe supporting structure 28 is disposed at the desireddistance from platform structure 10. Structure 28 includes a buoyantspar buoy 29 (see FIG. 2) coupled to gas line by suitable connectingmeans, such as connector 30 similar to connectors 26 (see also FIG. 1).Spar buoy 29 includes a generally vertical, tubular body member 31evacuated or filled with a suitable buoyant material, such aspolyurethane foam, as for example, four pounds per cubic feet indensity. A similar buoyant material-filled body member 32 may be securedto body member 31 generally perpendicular thereto and on the upperportion thereof for stabilizing the spar buoy 29 and providingadditional buoyancy. Suitable braces 33 may extend between members 31and 32 and be secured thereto for reinforcing the members.

Gas line 20 preferably includes a second riser portion 34 extendinggenerally horizontally from connector 30, then upwardly through bodymember 31 as shown in dotted lines in FIG. 2. At its upper end, riserportion 34 is preferably detachably secured, as through a releasableconnector 35, to a gas flare pipe 36. A bracket 37 having a pin 38thereon, is mounted on the lower end of spar buoy 29. A wireline 39 issecured to bracket 37 as will be discussed hereinbelow.

Thus, referring now to FIG. 3, wireline 39 includes a sleeve 40 at itsextremity which carries a socket portion 41 for passing over pin 38 withpivotal movement therebetween. Pin 38 further includes a suitableaperture 42 therein for receiving a securing pin 43 therethrough forfirmly and pivotally securing wireline 39 to spar buoy 29. Spar buoy 29further includes a plurality of brackets, as for example, bracket 44(FIG. 3) and bracket 45 (FIG. 2) secured to the outer surface thereof.Thus, as seen in FIGS. 1 and 2, the upper end of wire line 39 isattached to spar buoy 29 by bracket 45, passes down through an aperture46 in body member 32, then through a conventional wireline clip 47mounted on bracket 44 (see also FIG. 3).

Referring now to FIG. 4, wireline 39 next passes around the sheave 48 ofa toggle block 49 pivotally connected through pin 50 to an anchorconnecting pad-eye 51.

.Any suitable anchoring connecting means may be used to pivotallyconnect pad-eye 51 to Weight 52. Further, any suitable weight may beused. Thus, weight 52 ma have a pad-eye 53 at its upper end having atleast a pair of upwardly extending flanges 54 having suitable aperturesextending therethrough. The lower portion of pad-eye 51 preferably formsa tubular opening 55 therein. A connecting pin 56 preferably extendsthrough both opening 55 and the apertures in flanges 54 in such a mannerthat pad-eye 51 is adapted to rotate about pin 56 and thus about pad-eye53. Finally, connecting pin 56 preferably includes movement limitingmeans in the form of stops 57 for limiting the lateral movement of pin56.

Referring once again to FIG. 1, it can be seen that the overall lengthof wireline 39 between the lower end of spar buoy 29 and weight 52 maybe relatively great compared to the overall length of spar buoy 29. Sparbuoy 29 may include means thereon for varying the buoyancy thereof, suchas, for example, apertures therein (not shown) for selectively removingand adding portions of the buoyant material. As discussed hereinabove,the second portion of gas pipe 20 preferably extends from platformstructure 10 to a distance below the mean water line 58 of the body ofwater 12. Further, the gas flare pipe 36 also extends above the meanwater line 58. A burner tip 59 is provided on gas flare pipe 36 andsuitable means,

such as a ladder (not shown) may extend from body member 32 on spar buoy29 to the burner tip 59 for lighting the same.

In operation, the first riser portion 21 of gas line 20 is connected topipe portion 24, thus providing tfluid communication with pipe string17. The second portion 25 of gas line 20 is connected, at one endthrough connector 26, to riser portion 21 and at the other end, throughconnector 30, to the second riser portion 34 passing through spar buoy2'9. Spar buoy 29 is anchored to weight 52 through wireline 39 and theoverall length of wireline 39 is adjusted so as to maintain spar buoy 29at its desired location in ocean 12 with respect to mean water line 58.The buoyancy of spar buoy 29 is set so as to maintain gas flare pipe 36,at the upper end thereof, above the mean water line 58 and in asubstantially vertical position in ocean 12. Weights 27 may then beadded along the second portion 25' of gas line 20 so as to vary thenegative buoyancy thereof. Finally, burner tip 59 is ignited and wastegases from well 16 are burned off to the atmosphere.

-In this manner, the gas flare pipe support 28 described hereinabovepermits the gas flare pipe 36 to be deflected away from its uprightsubstantially vertical position and immediately right itself. The slightnegative buoyancy imparted to gas line 20 through weights 26 maintainsthe hose 25 below the anticipated draft of passing boats. The wireline39 gives the flexibility to the spar buoy 29 necessary to permit thestructure 28 to flex when subjected to water action, external forces,etc.

I claim as my invention:

1. Apparatus for conducting waste gas produced from an offshore wellextending into the floor of a body of water to a remote locationpreparatory to burning ofl. said waste gas, said apparatus comprising:

a platform structure associated with said well;

a first riser portion extending down along said platform structure, saidfirst riser being fixedly secured to said platform structure;

a horizontal portion extending generally outwardly from said platformstructure to a remote location, said horizontal portion being fiangibl'yconnected at one end to said first riser, said horizontal portionincluding at least one flexible hose section;

a second riser portion fiangibly connected at its lower end to saidhorizontal portion, said second riser portion extending from a generallyhorizontal position to a substantially vertical position at its upperend;

a gas flare pipe having a burner tip thereon, said gas flare pipe beingdetachably connected to said second riser portion at its uper end;

buoyancy means surrounding said second riser portion, said buoyancymeans being suitably connected to said second riser portion therebymaintaining said gas flare pipe in a substantially vertical position insaid body of water with respect to the floor thereof;

a Weight member disposed on the floor of said body of water; and

an elongated flexible cable means, one end of said cable being suitablyconnected to the outer surface of said buoyancy means, said cablepassing around a sheave pivotally connected to said weight member andterminating at a pivotal connection disposed on the lower end of saidbuoyancy means whereby the overall length of said elongated flexiblecable means is adjusted so as to maintain the buoyancy means in asubstantially vertical position at a desired location in a body ofwater.

2. The apparatus of claim 1 wherein said buoyancy means comprises afirst tubular body member; and

a second body member generally perpendicular to said first tubularmember, said second body member being secured to said first tubular bodymember thereby stabilizing said first tubular body member.

'3. The buoyancy means of claim 2 wherein said first tubular member isevacuated thereby providing additional buoyancy.

4. The buoyancy means of claim 2 wherein said first tubular member isfilled with a buoyant material.

5. The apparatus of claim 1 wherein said second portion further includesa plurality of removable hose weights thereby varying the buoyancy ofsaid horizontal portion to maintain said horizontal portion at somepoint substantially above the floor of said body of water.

References Cited UNITED STATES PATENTS EDWARD G. FAVORS, PrimaryExaminer US. Cl. X.R.

